1. Field of the Invention
The present invention relates to a reciprocating compressor in which a plurality of gas compression means having a cylinder and a piston is provided, the pistons of each gas compression means are formed to cooperate by converting a rotating motion of a crankshaft provided on a driving source to a reciprocating motion.
2. Detailed Description of the Prior Art
In a normal reciprocating compressor, one gas compression means having a cylinder and a piston is provided, while there has been a reciprocating compressor having a plurality of gas compression means conventionally. In such reciprocating compressor having a plurality of gas compression means, for embodiment as shown by FIG. 9(a), three gas compression means 101, 102, 103 having the cylinders and the pistons are oppositely arranged to achieve a reciprocating motion of the piston on orthogonal axis 105, 106, it is known that gas is compressed and high-pressurized from the gas compression means 101 in turns and that the gas compression means 103 is designed to be a final stage high pressure compression means.
In the reciprocating compressor 100, a pair of opposite pistons 51, 53 is connected to a yoke 1A, the other pair of opposite pistons 52, 54 is connected to a yoke 1B of which phase is shifted to an angle of 90 degrees. The compressor having a scotch yoke mechanism that a crankshaft 57 is rotated by a rotor 56 of an electric drive mechanism 55 as shown by FIG. 9 (b), a crank pin 58 is eccentrically rotated around the crankshaft 57, a pair of pistons 51, 53 is reciprocated only in the direction of an axis 105 and the other pair of pistons 52, 54 is reciprocated in only the direction of the axis 106.
As shown by FIG. 11 as a model, the scotch yoke mechanism is a kind of double slide crank mechanism to convert the rotating motion to the reciprocating motion or to convert the reciprocating motion to the rotating motion. In this case the rotating motion is converted to the reciprocating motion, in the scotch yoke mechanism having the yokes 1A, 1B, a crank pin 58 is attached between a lower balancer 59 and an upper balancer 60 which are mounted on a crankshaft 57 as shown by FIG. 10 and is engaged with yokes 1A, 1B, thereby the vibration or the like of the compressor is controlled and the compression can be operated in stable.
In the reciprocating compressor 100 described hereinbefore, it is composed that in accordance with an increase of compression stages, diameters of the cylinder and the piston of the gas compression means toward the high pressure side are designed to be smaller and each compression means is engaged and cooperated with the crank pin so as to actuate in a process of shifting its phase to a determined angle.
In the conventional reciprocating compressors, the compressed gas are highly pressurized one after another to achieve a predetermined gas pressure, however due to less inner volume of each gas compression means toward the high pressure side, the volume of the final discharged compression gas is decreased. In accordance with an object, for embodiment, for using the compressor for a gas supply stand for natural gas vehicles, a gas injection molding machine, an electric insulating gas (6-sulfur fluoride) collecting device, carbon dioxide coolant and refrigerating cycle and the like, especially it is requested to supply a large volume of compressed gas. To correspond with these requirement, the inner volume thereof can be increased by providing a large diameter of the cylinder and the piston of the compression means, however it will cause a large sizing of the compressor, an increase of electric consumption of the electric drive portion and a high cost. Further to use a plurality of compressors will cause an increase of space where compressors are located and an increase of the cost and the like.
It is the first object of the present invention that in a reciprocating compressor having a plurality of gas compression means, the volume of discharged gas can be increased without using a plurality of compressors.
Further in the conventional reciprocating compressor, the pulsation is caused by a discharged gas around the discharge port of each gas compression means 101, 102, 103 to make a vibration or a noise of the compressor. Therefore in conventional compressor, a muffler tube (not shown) is attached to the connecting tube with each gas compression means 101, 102, 103 to decrease the pulsation of discharged gas. However it is necessary to cut and remove a part of the connecting tube for mounting the muffler tube and to weld the muffler tube thereto, the troublesome working is caused, further the main body of the compressor is large-sized due to a larger diameter of the muffler tube than the outer diameter of the connecting tube and it has caused an increase of the cost due to an increase of manufacturing processes and of parts. The conventional muffler tube is inferior in its durability and has a problem of easily damaged by a high pressurized discharging gas.
It is the second object of the present invention to provide a reciprocating compressor to which the muffler is easily attached, which is designed in compact, in which a decrease of the cost of manufacturing and an improvement of its durability can be achieved.
Further in the conventional reciprocating compressors, in order to achieve a constant rotating speed of the crankshaft and to provide an stationary torque thereof, a flywheel is mounted on the lower end portion of the crankshaft. For attaching the flywheel, conventionally, for embodiment as shown in FIG. 6, a shaft hole 61a of the fly wheel 61 is shrinkage fit to the lower end portion of the crankshaft 57 which is projected from the shaft hole of the rotor 56. While an external thread is provided at the lower end portion of the crankshaft 57 and the internal thread is provided at the shaft hole of the flywheel 61 to be engaged with each other for receiving the flywheel. In accordance with conventional means for attaching flywheel, the attachment work is troublesome, further it is difficult to adjust respective axis of the crankshaft 57 and of the flywheel 61, and a slight movement will be caused since an axial line of the flywheel 61 is incliningly attached.
It is the third object of the present invention to provide the reciprocating compressor improved in easy attachment work of the flywheel and in an easy adjustment with the crankshaft to prevent the shaft from shifting.
Furthermore in the conventional reciprocating compressor, in order to increase the volume of discharged gas, gas compressed in a plurality of gas compression means are joined at the one place by connecting tube and are discharged in concentration. In this case, the compression performance of each gas compression means is set to be identical by designing the cylinder and the piston to be same size, the compression action of each gas compression means is shifted with a certain intervals in accordance with a rotation of the crank pin, for embodiment, the compressor is so comprised that compressed gas flow is joined by connecting tubes to cylinder head which is provided in one gas compression means and the compressed gas is discharged in concentration from the cylinder head. However in such concentrate discharging type compressor, since compressed gas flows are joined via a plurality of connecting tubes into the cylinder head to interfere with each other, a large pulsation is caused. Therefore, the muffler is provided in each connecting tube to decrease the pulsation of discharged gas from each gas compression means, however it is troublesome to attach the muffler, moreover the increase of the cost due to large number of parts has been caused and there has been a problem of large sized main body of the compressor and the like.
It is the fourth object of the present invention to provide the reciprocating compressor of the type improved in decreasing the pulsation due to interference of the compressed gas flows which are joined without attaching the muffler in the connecting tube.